Blue monoazo dye.



UNITED STATES PATENT OFFICE.

OSKAR KALTVVASSER AND HUGO JAESSCHIN, OF BERLIN, GERMANY, ASSIGNORS TOAOTIEN-GESELLSCHAFT FUR ANILIN FABRIKATION,

OF SAME PLACE.

BLUE MONOAZO DYE.

SPECIFICATION forming part of Letters Patent N 0. 683,119, datedSeptember 24, 1901. Application filed July 12, 1901. Serial No. 67,999.(No specimens.)

To all whom it may concern:

Be it known that We, OSKAR KALTWASSER and HUGO J AESSCHIN, of Berlin, inthe Kingdom of Prussia, German Empire, have invented new and usefulImprovements in the Production of Mordant-Dyeing MonoazoColoring-Matter; and we do hereby declare that the following is a full,clear, and exact description thereof, which will enable others skilledin the art to which it appertains to make and use the same.

We have found that a valuable monoazo dyestuif is produced if the diazocompound derived from 4-chloro-2-a1nidophenol sulfonic acid is combinedwith the 1.8-amidonaphthol- 2.4-disulfonic acid. This dyestuff whenfixed on wool with the aid of copper salts yields blue shades, which aredistinguished by their extraordinary clearness. Moreover, theyareneither uneven nord ull,whi oh inconveniences will often occur if dyeingwit-h coloring-matters susceptible of forming copper lakes is carriedout directly in an acid-bath on the addition of copper salts.

For the production of the a-chloro-fl-amidophenol sulfonic acid employedas a parent .material we proceed as follows: Twenty-five kilos of4t-chloro-2-nitrophenol are heated with a solution of one hundred kilosof sodium bisulfite and five hundred liters of water in a Vesselcombined with a reflux-condenser, and the mixture is kept boiling untilthe 4-chloro- 2-nitrophenol has disappeared, a clear solution thus beingformed. One hundred kilos of hydrochloric acid (specific gravity 12Baum) are now added thereto and the mass is boiled for sometime more inorder to expel the excess of sulfurous acid. -On refrigeration the4-chloro-Z-amidophenol sulfonic acid separates as a crystalline mass,easily soluble in boiling water, hardly soluble in cold water or inalcohol. Its sodium salt crystallizes from hot water in the form ofshining leaflets.

In order to transform the 4-chloro-2-amidophenol sulfonic acid into thenew inonoazo dyestuff, we proceed as follows: 22.3 kilos of4-chl0ro-2-amidophen0l sulfonic acid are diazotized in the well-knownway by means of seven parts of sodium nitrite and mineral acid. Theyellowish diazo solution thus formed is run into a solution ofthirty-two kilos of 1.8- amidonaphthol-2.4t-disulfonic acid,care beingtaken to keep the mixture alkaline by the addition of sodium carbonate.The solution is then acidulated,and the new disazo dyestuff isprecipitated by the addition of common salt in the form of its acidsodium salt. It is filtered, pressed, and dried.

The result is not materially changed if for the above-described4-chloro-2-amidophenol sulfonic acid the isomeric sulfo-acid issubstituted, which may be obtained by introducing one part by weight of4-cl1'loro-2-amidophenol into four parts of sulfuric acid mono= hydrate,heating the mixture gently for some time, and finally pouring it intoice-water.

The new dyestuif forms in the dry state a dark powder, easily soluble inwater to a bluish-red solution, the coloration of which changes tored-violet on addition of sodium carbonate and to afine red on theaddition of caustic soda lye. The dye dissolves easily in concentratedsulfuric acid, forming a red- Violet solution, which by dilution withice- Water turns bluish -red. It is but hardly soluble in alcohol to abluish-red solution. When fixed on wool with the aid of copper salts, ityields fine blue shades, distinguished by their extraordinary fastness.

Having thus described our invention and in what manner the same is to becarried out, What we claim is- The new monoazo dye obtained by combining diazotized 4t-chloro-2-amidophenol sulfonic acid with1.8-amidonaphthol-2.4-disulfonic acids; said dye being in the form ofits acid sodium salt a dark powder, easily soluble in water to abluish-red solution the coloration of which changes to red-violet on theaddition of sodium carbonate and .to a fine red on the addition ofcaustic-soda lye; the dye dissolving easily in concentrated sulfuricacid to a red-violet solution, which by dilution with ice-water turnsbluish-red; being hardly soluble in alcohol to a bluish-red solution;producing on wool, when fixed with the aid of copper salts, fine blueshades of an ex traordinary fastness.

In witness whereof we have hereunto signed our names, this 21st day ofJune, 1901, in the presence of two subscribing witnesses.

OSKAR KALTWASSER. HUGO JAESSOHIN.

Witnesses:

WOLDEMAR HAUPT, HENRY HASPER.

